Since the invention of the windscreen way back in 1904, it has continued to evolve and improve as an essential safety feature of the vehicles that we drive today. Read on to learn more about how the modern day shatterproof windscreen is manufactured.

1. How Shatterproof Windscreens Are Made
Before 1904, all vehicles had an open-air design, resulting in motorists having to wear
goggles in order to protect their eyes from wind and debris. 1
The very first windscreen was
made out of ordinary glass which, despite getting rid of the need to sport protective
eyewear, ultimately led to a few nasty accidents as a result of broken glass injuring drivers.
By the year 1917, mostly due to a number of lawsuits being filed against car manufacturers,
the design and structure of the windscreen was changed quite drastically. For starters,
windscreens started to be manufactured using a much hardier type of glass. Although not
nearly as flimsy as ordinary glass – the hardened glass shattered into smaller, less harmful
pieces when broken – the windshield could still be easily damaged by something as small as
a stone. In 1919, Henry Ford was the brains behind the operation that sought to further
improve the design of the windscreen. He began to use the process of laminating in an
effort to strengthen windshield glass and reduce the chances of it shattering on impact. The
design of these new windscreens included two layers of glass merged together by a single
layer of cellulose. It was this inner layer of cellulose that made it so difficult for the glass to
shatter. 2
What Are Modern Windscreens Made of?
It has taken a long time to get windscreens to be as safe and as reliable as they are today.
Luckily, in modern times, windscreens are as much of a safety feature of a vehicle as
seatbelts and air bags are. The aim is to create a windscreen that is completely shatterproof
– i.e. even when hit with a strong force, the windscreen remains in one piece. In order to
achieve this, there are a few essential ingredients that every car manufacturer requires.
These ingredients include:
 Silica sand;
 Dolomite;
 Soda ash;
 Cullet;
 Limestone;
 Aluminium oxide;
 Potassium oxide.
The Manufacturing Process
Henry Ford’s process of using three layers when creating a windscreen still stands today.
However, instead of using an inner layer of cellulose, a layer of poly-vinyl butyral is placed in
between the two layers of tempered glass. The ‘Float Method’, the most common method
used in the manufacturing of windshields, works as follows:

2.  To begin with, water and all of the ingredients are mixed together in a refractory
tank. Once mixed, they are subjected to extreme temperatures so that they melt.
The molten ingredients are then transferred to a second tank which is known as the
‘float chamber’.
 Next, the molten glass enters the ‘lehr’ where it is cooled down.
 The sheet of glass is then cut according to size requirements with the help of a scribe
– which is a specialised diamond cutting tool.
 The newly cut glass is placed into a mould and is heated gradually so that it softens
and fits perfectly into the desired shape. Once it has ‘sagged’ into the mould, the
glass is then cooled down quickly so that it maintains this shape and hardens.
 The final step is when two layers of tempered glass are placed over the layer of poly-
vinyl butyral, sandwiching it between them. All three layers are then gently heated
and pressed between rollers. The result is a strong fusion of all of the layers and an
incredibly strong windscreen.
Windshields have come a long way over the last hundred years, eventually transforming
into the shatterproof versions that we, as motorists, rely on each and every day. With this in
mind, it is almost certain that this windscreen technology can only continue to improve as
more time goes by.
Sources
1
http://www.carwindshields.info/how-a-windshield-is-made
2
http://en.wikipedia.org/wiki/Windshield